How to calculate 20 percent of something?

Can you draw an isosceles triangle with only one 80 degree angle?

∠aed is formed inside a circle by two intersecting chords. if minor arc bd = 70 and minor arc ac = 180, what is the measure of ∠ aed? a) 45° b) 50° c) 55° d) 60°

Danielle earns a 7.25% commission on everything she sells at the electronics store where she works. she also earns a base salary of $750 per week. what were her sales last week if her total earnings for the week were $1,076.25?